Cho hình vuông \(ABCD\) có cạnh bằng \(a\). Người ta dựng hình vuông \({A_1}{B_1}{C_1}{D_1}\) có cạnh bằng \(\dfrac{1}{2}\) đường chéo của hình vuông \(ABCD\); dựng hình vuông \({A_2}{B_2}{C_2}{D_2}\) có cạnh bằng \(\dfrac{1}{2}\) đường chéo của hình vuông \({A_1}{B_1}{C_1}{D_1}\) và cứ tiếp tục như vậy. Giả sử cách dựng trên có thể tiến ra vô hạn. Nếu tổng diện tích  của tất cả các hình vuông \(ABCD,{A_1}{B_1}{C_1}{D_1},{A_2}{B_2}{C_2}{D_2}...\) bằng \(8\) thì \(a\) bằng:  

Choose the best answer for the following sentence:

My mother is a caring woman and always _____________ of others.
 

Choose the best answer for the following sentence:

Only by _____________ for the exam carefully can you earn good mark and come up to your parents' expectations.
 

Find a mistake in the four underlined parts of the sentence and correct it:

Facial expression involves some of smallest body movements, but its impact may be greater than any other body language.

Find a mistake in the four underlined parts of the sentence and correct it:

Smiles and grimace can be very effective used in conversation, but more commonly, we do not tend to think that nonverbal physical response may be communicating.

Find a mistake in the four underlined parts of the sentence and correct it:

Teachers often use eye contact in the classroom to decide who is prepared to answer a question, or that didn’t complete his homework assignment.

Find a mistake in the four underlined parts of the sentence and correct it:

Beside words the human face is the primary source of information for express an individual’s internal feelings.

Read the passage below and choose the correct answer:

       Body postures and movements are frequently indicators of self-confidence, energy, fatigue, or status. Cognitively, gestures operate to clarify, contradict, or replace verbal messages. Gestures also serve an important function with regard to regulating the flow of conversation. For example, if a student is talking about something in front of the class, single nods of the head from the teacher will likely cause that student to continue and perhaps more elaborate. Postures as well as gestures are used to indicate attitudes, status, affective moods, approval, deception, warmth, and other variables related to conversation interaction.
      The saying "A picture is worth a thousand words" well describes the meaning of facial expressions. Facial appearance - including wrinkles, muscle tone, skin coloration, and eye color-offers enduring cues that reveal information about age, sex, race, ethnic origin, and status.
      A less permanent second set of facial cues-including length of hair, hairstyle, cleanliness, and facial hair-relate to an individual's idea of beauty. A third group of facial markers are momentary expressions that signal that cause changes in the forehead, eyebrows, eyelids, cheeks, nose, lips, and chin, such as raising the eyebrows, wrinkling the brow, curling the lip.
    Some facial expressions are readily visible, while others are fleeting. Both types can positively or negatively reinforce the spoken words and convey cues concerning emotions and attitudes.

1. Gestures ______________ .
A. can do nothing with a conversation
B. can clarify the meaning of verbal messages
C. may interrupt the flow of a conversation
D. can end a conversation more quickly than usual

2. A nod of the head from the teacher will likely ask his student to ____________ what he is saying.
A. go on             B. give up              C. put off              D. throw away

3. According to the writer, "A picture is worth a thousand words" means _____________ .
A. a picture of a face is more valuable than a thousand words
B. a picture is more important than a thousand words
C. facial gestures can convey a lot of meanings
D. he has just bought a picture with a thousand words on it

4. How many categories of facial expressions are mentioned?
A. 2             B. 3                C. 4                 D. 5

5. Facial expressions ________________.
A. cannot convey emotions                        B. cannot reinforce spoken words
C. can only express negative attitudes         D. can be either visible or fleeting

Choose the word that has the underlined part pronounced differently from the rest:

through               other              everything                thanks

Choose the word that has the underlined part pronounced differently from the rest:

facial                communicate                contact                 carpet

Choose the word that has the underlined part pronounced differently from the rest:

sometimes               gestures              interests                examples